The small diameters of glass optical fibers make it very difficult for making connections between two fibers. Since most of the light travels through the small central core region of the fibers it is important that the cores of the fibers line up accurately in order to prevent the loss of light in transfer between cores of the two fibers to be connected. Another problem involved in coupling between optical fibers is the difference in diameter and the uncertainty as to the effective location of the core center relative to the outer perimeter of the fiber.
One effective method for overcoming the problems involved in coupling between adjoining optical fiber ends is that provided in U.S. patent application Ser. No. 613,390, filed Sept. 15, 1975 and assigned to the common assignee of the instant invention. This method allows for accurate alignment between optical fibers by providing three tangentially contacting parallel rods as aligning members and inserts the ends of the fibers to be joined into the interstice formed between the tangential points of contact of the rods. The carefully controlled dimensional geometry of the rods insures good alignment between the fibers since the fibers contact each of the rods at one point which in turn provides three carefully controlled reference points.
The purpose of this invention is to provide precision formed optical fiber reference surfaces which allow for accurate alignment between the fibers without the need of auxiliary precision alignment rods and without the necessity of removing the protective plastic or optical plastic cladding.